1. Field of the Invention
The present invention relates to a liquid crystal display panel and more particularly to a liquid crystal display panel that is adaptive for patterning a color filter of the liquid crystal display panel without using a photolithography process, and a fabricating method thereof.
2. Description of the Related Art
FIG. 1 is a sectional diagram representing a liquid crystal display panel of the prior art.
The liquid crystal display panel shown in FIG. 1 includes an upper array substrate having a black matrix 54, a color filter 56, an over coat layer 57, a common electrode 68, a column spacer 63 and an upper alignment film 58 which are sequentially formed on an upper substrate 52; a lower array substrate having a TFT, a pixel electrode 66 and a lower alignment film 88 which are formed on a lower substrate 82; and a liquid crystal (not shown) injected into an inner space between the upper array substrate and the lower array substrate.
In the upper array substrate, the black matrix 54 is formed on the upper substrate 52 corresponding to a TFT area of a lower plate and an area of gate lines and data lines (not shown), and there is provided a cell area where a color filter 56 is formed. The black matrix 54 prevents light leakage and absorbs an external light, thereby acting to increase contrast. The color filter 56 is formed at the cell area divided by the black matrix 54. The color filter 56 is formed by R, G and B to realize R, G and B colors. The over coat layer 57 is formed to cover the color filter to flatten the upper substrate 52. A common voltage is supplied to the common electrode 68 to control the movement of liquid crystal. The column spacer 63 acts to keep a cell gap between the upper substrate 52 and the lower substrate 82. On the other hand, it is possible that there is no over coat layer 57 in a twisted nematic TN mode where a vertical direction electric field is used, and the common electrode 68 might be formed in the lower array substrate in case of an In-Plane Switch IPS mode where a horizontal direction electric field is used.
In the lower array substrate, the TFT includes a gate electrode 59 formed on the lower substrate 82 along with a gate line (not shown); semiconductor layers 97, 64 overlapping the gate electrode 59 with a gate insulating film therebetween; and source/drain electrodes 90, 92 formed together with a data line (not shown) with the semiconductor layers 97, 64 therebetween. The TFT 37 supplies a pixel signal from the data line to the pixel electrode 66 in response to a scan signal from the gate line.
The pixel electrode 66 is in contact with a drain electrode 92 of the TFT with a protective film 100 therebetween, wherein the protective film is of a transparent conductive material with high light transmissivity. Upper/lower alignment films 58, 88 for liquid crystal alignment are formed by performing a rubbing process after spreading an alignment material such as polyimide.
FIGS. 2A to 2F are sectional diagrams representing a fabricating method of an upper array substrate of the prior art step by step.
Firstly, after an opaque metal, e.g., Chrome Cr, is deposited on the upper substrate 52, the opaque material is patterned by a photolithography using a first mask and an etching process, thereby forming the black matrix 54 as shown in FIG. 2A. Herein, the opaque resin can be used as a black matrix material.
After a red resin is deposited on the upper substrate where the black matrix 54 is formed, the red resin is patterned by photolithography using a second mask and the etching process, thereby forming a red color filter R as shown in FIG. 2B.
After a green resin is deposited on the upper substrate where the red color filter R is formed, the green resin G is patterned by photolithography using a third mask and the etching process, thereby forming a green color filter G as shown in FIG. 2C. After a blue resin is deposited on the upper substrate 52 where the green color filter G is formed, the blue resin is patterned by photolithography using a fourth mask and the etching process, thereby forming a blue color filter B as shown in FIG. 2D. Hereby, the red, green, blue color filters 56 are formed.
After a transparent conductive material is deposited on the upper substrate 52 where the color filter 56 is formed, by a deposition method such as sputtering, and then it is patterned, thereby forming the common electrode 68 as shown in FIG. 2E. On the other hand, the over coat layer 57 is located between the common electrode 68 and the color filter 57 in case of the IPS mode.
A spacer material is patterned on the upper substrate 52 where the common electrode 68 is formed, by the photolithography using a fifth mask and an etching process, thereby forming a column spacer 63 as shown in FIG. 2F.
Thus, in order to form the upper array substrate of the liquid crystal display panel of the prior art, at least 5 mask processes are required. Each of the mask processes includes the photolithography which is a series of photography processes having a spread of photo-resist, a mask alignment, an exposure and a development. In such a photolithography process, its required time for process is long, the waste of the photo-resist and a developing solution that develops the photo-resist pattern is big, and expensive equipments such as exposure equipment are required. As a result, there is a problem that the fabricating process is complicated and a fabricating cost of the liquid crystal display panel is increased.